Summary: WHO-sponsored Internaitonal Collabrative Study on evaluation of MAPREC for type 3 and type 2 OPV wwas completed in previous years. CBER has prepared reference materials, controls, and SOP for MAPREC test for type-1 OPV . NIBSC ampouled the materials and distributed among the participants of the study. Currently the participants are tesing the materials and the role of CBER is to facilitate troubleshooting and interpreattion of results. It is expected that the Study will be completed at the end of 2001. The project will be continued in FY 02.